In 14 years and 350+ nights of tarp use in ID desert, alpine west, S. Cal desert, Sierra's, Winds, Colorado CDT, Pyreenes, French Alps, AT thru-hike, PCT thru-hike, etc. I've had 2 or 3 individual ants crawl over me. None considered biting me.
Just don't camp on top of a hill and you will be OK.

Amtrak